Cold forming apparatus and method



Jan. 5, 1960 c. A. NICHOLS 2,919,611

COLD FORMING APPARATUS AND METHOD Filed Aug. 3, 1955 2 Sheets-Sheet 1INVEN TOR.

% A. 2% HIS ATTOR NE) Jan. 5, 1960 c. A. NICHOLS cow FORMING APPARATUSAND METHOD Filed Aug. 5, 1955 2 Sheets-Sheet 2 H/J' ATTURNE'Y UnitedStates Patent COLD FORMING APPARATUS AND METHOD Charles A. Nichols,Anderson, Ind., assignor to General Motors Corporation, Detroit, Mich.,a corporation of Delaware Application August 3, 1955, Serial No. 526,304

' 2 Claims. CI. 7838) This invention relates to a metal workingapparatus and methods and is particularly concerned with a machine andmethod for finishing the edges of metal parts such as compressor blades.

It is the main object of the invention to provide a machine and methodof operating same wherein a metal object, such as a compressor blade,having a sharp edge or edges thereon may be cold worked to form arounded edge thereon.

A still further object of the invention is to provide a peening orswaging device which will operate on the edge of a metal part, such as acompressor blade, and which will round oh the sharp corners of the edgeand bring the width of the part to a predetermined and desireddimension.

A still further object of the invention is toprovide a machine forpeening or swaging the edge or edges of a metal part for providing aradius thereon while simultaneously bringing the width of the part to apredetermined desired dimension which comprises a reciprocating swagingtool driven by a rotatable hammer wherein the amplitude of stroke of thetool is predetermined for swaging the edge e; edges of the metal part toa desired shape and dimension. During rotation of the hammer, the fixurein which the metal part is held may be reciprocated relative to theswaging tool so that the swaging operation is progressively appliedalong the edge of the part being operated upon.

Further objects and advantages of the present invention will be apparentfrom the following description, ref erence being had to the accompanyingdrawings, where in a preferred form of the invention is clearly shown.

In the drawings:

Figure 1 :is a view in perspective of an apparatus suit-- able forrounding the edges of a compressor blade;

Figure 2 is a view partly in section of the apparatus shown in Figure l;

Figure 3 is a view in perspective of a compressor blade prior to theswaging operation;

Figure 4 is a view in perspective of the same blade after the swagingoperation;

Figure 5 is a modification of the swaging mechanism wherein a springreturn is used on the swaging tool;

Figure 6 is a diagrammatic view of a hydraulic mechanism which may beused to reciprocate the part being swaged; and

Figure 7 is an enlarged sectional view of the blade in the swagingfixture.

It is desirable to finish the edges of metal parts in many instanceswherein the part comprises a more or less wire edge or sharp edge whichmust be rounded off to complete the manufacture of the part. This isaccomplished by many expedients such as grinding, machining as in ashaper, etc; Compressor blades such as are used in turbo-compressors,for example, require a high degree of accuracy in their dimensions andit is desirable in such parts to have rounded edges to reduce theresistance to movement in the air and likewise to cause the edges of theblades to be more resistant to erosion. For this reason the edges ofcompressor blades are preferably rounded and must be operated on in sucha manner that a high degree of accuracy in dimension is maintained. Thisoperation in the past has been carried out by precision grinding whichis botlrcostly and slow. The present invention is specifically directedto a method and apparatus for rounding the edges of such parts by asimple apparatus which maintains the dimensional tolerances required,while simultaneously carrying out the desired operation at a reducedcost over past methods.

Referring specifically to Figure 1, a swaging or peening apparatus isshown at 20 which includes a base 22 having a pair of slideways 24mounted thereon in which a vise-like carriage 26 is reciprocallymovable. A pair of standards 28 are mounted on the base 22 and supportat their upper end a plate 30 which is adjustable upon the standards 28through the use of adjustment means 32. The plate 30 has an aperture 34of rectilinear cross section machined therethrough which acts as abearing and guide for a piston-like element 36. The element 36 carriesat its lower end a swaging tool 38 having a groove 40 therein which hasthe desired conformation for the edge of the part to be swaged. Theupper end of the element 36 carries an anvil 42 made of hardened steel.Above the anvil 42 and element 36 is mounted a rotary hammer 44 whichcomprises a cylinder 46 having mounted therearound in equally spacedrelation a plurality of hardened steel hammer members 48 comprising barsset in spaced recesses in the cylinder 46. The bars are held in thecylinder 46 as noted in Figure 2 whereby they are interlocked thereindue to the recesses in the cylinder as noted at 50 which are slightlygreater than semicircular in cross section so that the bar-like hammermembers must be inserted into the recesses 50 from the ends of thecylinder. During rotation of the cylinder 46 these bar-like members 43may rotate within their recesses 50 for preventing excessive wearthereon. The rotary hammer 44 is carried by a shaft 52 whichis journaledin a bearing 54 carried by the rear portion of the plate 30. The end ofthe shaft 52 opposite the hammer 44 carries a pulley 56 which isattached by means of a belt 58 to a suitable driving motor (not shown).It is apparent in this instance that in place of the pulley 56 and belt58 suitable gearing may be utilized to drive the mechanism.

The carriage 26 has an upwardly turned end portion 69 thereon which isattached to one end of a piston 62 of a double acting air cylinder 64.The double acting air cylinder, which will be explained in more detailhereinafter, is adapted to reciprocate the carriage 26 at a suitablespeed.

The vise-like carriage 26 is adapted to carry a blade as shown at 76.The blade 70 is wedged in place on the carriage 26 by means of two nylonwedge blocks Y72. and 74 and a steel wedge block 76. The nylon blocksprevent injury to the blade surface. The lower edge of the blade 70rests in a groove 71 formed in a hardened metal insert '73 set in thecarriage 26. The groove 71 is identical in dimension to the groove 40 inthe member 38 if the two edges of the blade are to be swaged to the sameshape. It is apparent that diflerent cross section grooves may be usedto obtain desired results or the two opposed grooves may be diilerentone from the other as desired. The distance between the inner edge ofthe groove 40 of the swedging tool 38 and the inner edge of the groove71 of carriage 26 upon which the blade rests is adjusted to the finisheddimension of the blade. Thus, as the swaging device or tool 38 hits theblade edge it causes both edges to be swaged simultaneously.

Figure 3 shows a typical cross section of an unfinished blade 70 whileFigure 4 shows a cross section of the same blade 70 after swaging. Itwill be noted that the edges 80 thereon are rounded due to the swagingoperation.

In normal practice, during rotation of the hammer 44, the swaging tool38 and its supporting element 36 will bounce upwardly after eachdownward pressure stroke of the hammer elements 48 against the anvil.However, in some instances if the speed of the device is variedappreciably from the preferred speeds and if other factors are markedlychanged, it may be desirable to utilize a spring as noted at $8 inFigure as a positive return for the element 36. in this case, as thehammer presses the element 36 downwardly the spring 90 is compressedwhich then returns the element 36 to its upper position after the hammerelement 48 has passed.

In practice the hammer 46 is rotated at a speed sufficient to cause thehammer 44 to strike 4-800 strokes per minute on the element 36 whichmeans that the swaging tool 38 hits the edge of the blade 4800 t mes perminute. The speed of the swaging tool 38 is obviously controlled by thespeed of rotation of the hammer 44 and the number of hammer elements 48carried thereby. However, as previously mentioned a speed of 4800strokes per minute yields very satisfactory results. During the swagingoperation, as the swaging tool 33 is being struck at the above notedspeed, the carriage 26 is being reciprocated with respect to the swagingtool 33 at a speed of approximately one inch per second so that the edgeof the blade is hit approximately 80 times each .0l inch. When thecarriage 26 reaches the limit of movement in one direction the cylinderat reverses the direction of movement and causes the carriage to move inthe other direction at the same rate of speed. In this manner theswaging of the edge of the blade continues progressively until the edgeis rounded as desired and brought to the desired dimension.

During the swaging operation the metal at the edges of the blade iscrowded into the cooperating slots until it assumes the contour of theslots. Thus any desired cross section may be formed on the edges or" theblade by this machine and method, wherein opposed edges are to befinished.

While any suitable mechanism may be used for reciprocating the carriage26, a double acting cylinder as shown at 64 is preferred. in thisinstance as noted in Figue 6 the cylinder 64 is connected by means ofducts 109 and 192 to a double acting hydraulic valve 1 34 which is inturn connected to a pressure passage 106 and to two relief passages H38and 119. The back of the carriage 26 has a pair of adjustments 109thereon which are set to engage a reversing micro-switch 112 which inturn is electrically connected to two solenoids 114 and 116 on oppositeends of a piston 113 of the valve 164. When the switch 112 is inposition as shown in Figure 6, solenoid 114 is energ zed and causes thepiston Ill?) to be moved to the left as shown which allows fluid underpressure from passage 1% to pass through duct lltltl and cause piston 62in the cylinder 64 to move to the right and thereby pull the carriage 26in the same direction. Simultaneously, fluid that was in the cylinder 64at the right side of the piston is forced through duct W2 and outthrough passage 103. When the carriage 26 reaches the limit of movementto the right, adjustment 109 engages switch 112 to reverse its positionwhich deenergizes the solenoid 114 and energizes solenoid 116 which willpull the piston 118 to the right thereby permitting fluid under pressurein passage 1% to enter duct 102 and cause the piston 62 in cylinder 64to move to the left. Simultaneously fluid on the left side of the piston62 will exhaust through duct 1% and passage Til This action willcontinue as long as the circuit is ciosed through main switch E18whereby the carriage 26 will be moved in a reciprocating manner betweenthe limits of its movement as determined by the adjustments 199 on thecarriage 26 with respect to the switch 112.

It is apparent that various modifications of this controlling mechanismmay be used with equal success, the apparatus shown being exemplary ofone form of suitable apparatus.

While the forms of embodiment of the invention as herein disclosedconstitute preferred forms, it is to be understood that other formsmight be adopted, as may come within the scope of the claims whichfollow.

What is claimed is as follows:

1. A swaging machine for roundingopposed longitudinal edges of asheet-like metal part, comprising in combination; a base, a swaging toolsupport mounted on said base, a swaging tool carried by said support andreciprocable with respect thereto, a fixture associated with said basefor holding the sheet-like metal part on edge with one of thelongitudinal edges to be rounded exposed longitudinally thereof, asecond base in said fixture including a longitudinally extending groovetherein which groove has a longitudinal extent at least equal to thelength of the part to be swaged and a cross section similar to theultimately desired cross section of one of the edges to be rounded,clamping means for clamping the part with said one edge in the fixturegroove and for preventing transverse deformation of the part whilepermitting edgewise deformation of the edge portion in the fixturegroove, said fixture being so dimensioned that the longitudinal edge ofthe part opposed to the edge in said groove is exposed longitudinallythereof, a swaging tool support, a swaging tool including a groovetherein having a cross section similar to the ultimately desired crosssection of the edge of the part and carried by said support andreciprocable therein, means for reciprocating said swaging tool withrespect to its support for causing the tool to engage the exposed edgeof the part periodically and repeatedly with impact blows and forreacting the opposed edge of the part with impact blows against saidbase groove, and means for causing relative to and fro movement betweenthe fixture and the swaging tool whereby the swaging tool progressivelyand repeatedly engages all portions of the exposed edge of the partwhereby both edges of the part are rounded.

2. A swaging machine for rounding opposed longitudinal edges of asheet-like metal part, comprising in combination; a base, a swaging toolsupport mounted on said base, a swaging tool carried by said support andreciprocable with respect thereto, a fixture associated with said basefor holding the sheet-like metal part on edge with one of thelongitudinal edges to be rounded exposed longitudinally thereof, a basein said fixture including a longitudinally extending groove thereinwhich groove has a longitudinal extent at least equal to the length ofthe part to be swaged and a cross section similar to the ultimatelydesired cross section of one of the edges to be rounded, clamping meansfor clamping the part with said one edge in the fixture groove and forpreventing transverse deformation of the part while permitting edgewisedeformation of the edge portion in the fixture groove, said fixturebeing so dimensioned that the longitudinal edge of the part opposed tothe edge in said groove is exposed longitudinally thereof, means forreciprocating said swaging tool with respect to its support for causingthe tool to engage the exposed edge of the part periodically andrepeatedly with impact blows and for reacting the opposed edge of thepart with impact blows against said base groove, a carriage mounted onsaid base for reciprocally carrying said holding fixture, and means forreciprocating the holding fixture and its carriage to and fro wherebysaid swaging tool progressively and repeatedly engages all portions ofthe exposed edge of the part whereby both edge of the part are roundedsimultaneously throughout their longitudinal extent.

(References on following page) References Cited in the file of thispatent UNITED STATES PATENTS Kingman Dec. 15, 1874 Smith Oct. 4, 1892 5Jacobs Feb. 6, 1894 Fenner Dec. 16, 1902 Weston Feb. 25, 1913 TowsendJune 10, 1913 Arthur June 26, 1917 lo Brandt et al May 4, 1920 6 SussmanJan. 22, 1924 Calder Feb. 12, 1924 Dean Mar. 8, 192 7 Lawson June 20,1933 Cross Sept. 12, 1933 Newall Nov. 5, 1946 Garbe Jan. 22, 1957FOREIGN PATENTS Great Britain Mar. 11, 1953

